Analysis of the cause of coking due to insufficient current in the blower of CFB boilers (Those with experience, please read)
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While the boiler was operating normally, there was a sudden drop in the blower current. Coking accidents still occurred even after measures such as slag discharge were taken. After the coke deposits were removed, the cold-state tests proceeded normally (the motor’s three phases were balanced, current and voltage were within normal ranges, and the fan operated smoothly). However, after the furnace was started up, the current in the blower decreased again, leading to the formation of coke deposits. Thorough inspection after shutting down the furnace: 1) The location of the electric butterfly valve at the blower outlet matches the indication on the instrument. 2) There is no blockage in the exhaust flue at the blower outlet or in the bellows, and the air caps are in good condition. The motor inspection and bearing housing inspection are normal. 3) The particle size of the base material is normal. The cold-state test was normal, but after restarting the furnace, the motor current was low again. No choice but to add charcoal (it’s acceptable if the coal quality is poor); slag had to be removed frequently. After maintaining this condition for an hour, the motor current increased, so adding charcoal was stopped. Normal operation (the layer thickness must be strictly controlled, and the blower current remains about 10A lower than under normal conditions). ) Risks always exist. Currently, the fan motor current shows significant fluctuations (it remains on the low side), and the readings of the electric butterfly valve instruments also fluctuate greatly (which is abnormal as well). Suspected issues: 1) The actuator of the electric butterfly valve has a loose brake. (Posterior inspection and adjustment were carried out before ignition; the actuator’s manual control unit has been replaced with a new one.) 2) The motor poses a potential risk. (Electrician’s inspection shows normal conditions.) 3) The latch of the blower impeller is loose. (If it loosens, won’t the impeller fall off?) ) I really can’t think of any more tricks. Could an experienced friend help analyze what other possible causes there might be? Thank you very much!
I’ll give it a try myself: I went to check the motor speed again this afternoon. Rated speed is 1480 r/min, while the actual measured value is 1490 r/min. What exactly is the reason for the low motor current? My head is huge.
It is recommended that you check whether the opening of the intake air control valve is fully open, and whether there are any issues with the vanes of the control valve such as detachment, jamming, or damage to the slots – as this could lead to insufficient air intake
Also: What exactly is the impeller pin you mentioned?
A decrease in current is due to mechanical failures and blocked air ducts. Mechanical failures may be caused by slipping impellers; a common issue is blockages in the air ducts. Check whether the boiling condition of the ash and slag inside the furnace is normal.
The current of the blower is inversely proportional to the resistance； The greater the duct resistance or the thicker the material layer, the lower the blower current. I’m not sure about the combustion conditions of your boilers – is the feed returned manually or automatically? When the amount of return material is too large, it also causes the material layer to thicken and the current drawn by the blower to decrease, although the variation is not significant.